CLASSIFICATION OF PORPITA
PHYLUM :- COELENTRATA (Tissue grade, diploblastic and acoelomate. )
CLASS :- HYDROZOA (The hydroids and craspedote medusa )
ORDER :- SIPHONOPHORA (Polymorphic colonies with various polypoid and medusoid zooids.)
SUB-ORDER :- PHYSOPHORIDA (Upper end of colony contains float or pneumatophore, without swimming bells or bracts and with simplified cormidia. )
FAMILY :- CHONDROPHORAE (Float forms a disk like structure.)
GENUS :- Porpita
GEOGRAPHICAL DISTRIBUTION
It is found along the South Atlantic coast and occasionally near U.K. coast.
HABIT AND HABITAT
Porpita is marine and colonial, found in warm seas.
GENERAL CHARACTERSTICS OF PORPITA
- It superficially resembles a medusa. It is most modified siphonophore. The stem is shortened to a flat coenosarc which along with float forms a rounded disk having several concentric air chambers.
- Body is discoidal, enclosing a chambered, chitinous and porous shell, having air corresponding with pneumatophore of Physalia.
- A large gastrozooid, having central mouth is encircled by several blastostyles.
- Margin of disk contains numerous dactylozooids or tentacles armed with nematocysts.
- Nectocalyces or swimming bells are absent.
- Each air chamber opens to outside by a pair of pores.
- Space between the gastric cavity of the gastrozooid and the pneumatophore is occupied by a large cellular mass traversed by canals, the so-called liver, supposed to have an excretory function.
- The reproductive zooids are liberated as free medusae.
IDENTIFICATION
- The animal has central disc surrounded by tentacles and all above feature, hence it is Porpita.
